The present invention relates to a vacuum chamber packaging machine, and particularly to the system for sealing an opening of a package within the vacuum chamber.
In many packaging applications it is necessary to remove substantially all air from the interior of the package. Thus, many packaging machines have been developed that pull a vacuum through the open end of a package and then seal the open end while the vacuum is maintained. The package can contain a variety of products, but especially products that require a modified atmosphere, such as a sterilized and/or oxygen free environment. In addition, the process of vacuum packaging can draw the package tightly around the contents, thereby immobilizing the product within the package. Vacuum packaging is particularly valuable for sealing sterilized medical devices, implants and instruments. The sealed package may form a barrier such that if the device is sterilized after the vacuum packaging (via a penetration sterilization method such as, but not limited to, gamma irradiation or E-Beam irradiation), the device maintains its sterility over a period of time.
In the field of medical devices, it is commonplace for pre-packaged components to be provided to the medical personnel. The components are sterilized and must be maintained in sterile condition until the package is opened in the operating room. For instance, in certain orthopedic surgical procedures, components of an orthopedic implant are provided in a sterilized and sealed bag. The implant is cleaned and packaged in a controlled environment and then sterilized. In many cases, the vacuum, maintained by the seals of the package, prevents oxidation of the device in the package. It is of particular interest that the sterilization process may alter the molecular structure of the device and that the absence of oxygen often prohibits the oxygen from combining with the molecular structure of the device and prevents oxidation of the device. Under these conditions, it is essential that the seal and the vacuum be maintained in the product packaging to preserve the sterility and/or the material properties and shelf life of the implant.
For products such as medical implants, care must be taken with the product itself during the packaging and sealing process. Thus, unlike mass production of vacuum sealed products, such as food, medical implants are typically individually packaged and sealed by a packaging operator. Individual package machines are known that meet these low volume packaging requirements. One such system is sold by Multivac Sepp KG, and is depicted in U.S. Pat. No. 5,056,292. In this system, opposing sealing bars are clamped about the package opening and heated by an electrical pulse.
Impulse sealing systems, such as the system depicted in the '292 Patent, are very adequate to create a vacuum or air-tight seal of the package. However, impulse sealing systems suffer from some drawbacks. For instance, most impulse sealing systems must be “primed” before statistically capable sealing operations can begin. These priming cycles prepare the sealing bar for the quick bursts of electrical energy/voltage that will be subsequently used to instantaneously increase the temperature of the bar. The priming is necessary to build a baseline seal wire temperature such that subsequent sealing cycles will yield statistically capable and controlled seal strengths. The statistically capable and in controlled sealing process is required for medical device special processes, such as seal validation studies. Even still, the baseline temperature is in a constant state of thermal cooling until the next seal is initiated. While the impulse sealing process is generally reliable and repeatable, a deficient sealing temperature may or may not be known until a package seal has been attempted. If the seal is inadequate by visual examination, the package must be scrapped and the contents repackaged. If the baseline temperature cools excessively, the seal strength may not be statistically as strong as those with higher baseline temperatures.
There remains a need for a vacuum packaging machine that reliably produces a sealed vacuum package.